A balanced equation is like a recipe. A recipe tells you how much of each ingredient to put in a cheesecake (or whatever). A balanced equation tells you how many of each molecule are involved in the reaction.

Let’s say a cheesecake recipe takes four cream cheese, three eggs, and one cup of sugar. It’s a balanced equation for cheesecake:

Food Ratio Problem 1: What if you need to make 5 cheesecakes? How many packages of cream cheese do you need to buy?

Answer: You need four cream cheese for every one cheesecake. You can write that ratio as a fraction:

If this was a chemistry problem that you couldn’t do in your head, you would multiply the amount of cheesecake you want by this fraction to get the answer:

(Known Amount) x (Mole Ratio) = Answer

You need 20 packages of cream cheese.

This was setup to make “Cheesecake” units cancel out on the bottom of the mole fraction like this:

Here’s another type of problem: let’s say I have 24 packages of cream cheese. What’s the right number of eggs to go with 24 packages of cream cheese?

Food Ratio:

This time cream cheese goes on the bottom since we want it to cancel out when we calculate the answer:

(Known Amount) x (Mole Ratio) = Answer

The math involved is simply this:

Mole Ratios / Chemical Reaction Recipes

Coefficients in a balanced chemical equations show mole ratios.

Example Balanced Equation:

The “2” in “2KClO₃” is the first coefficient in this equation.

Mole Ratio Example Questions
Example 1: If 12 moles of KClO₃ are used up, how many moles of O₂ are produced?

Mole Ratio:

• • We have KClO₃ on the bottom since so it will cancel out.
  • O₂ is on top since that’s what we want to calculate.
  • The “3” in “3O₂” comes from the balanced equation.
  • The “2” in “3KClO₃” comes from the balanced equation.

   

• (Known Amount) x (Mole Ratio) = Answer